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A Bell Inequality Analog in Quantum Measure Theory

David Craig·Fay Dowker·Joe Henson·Seth Major·David Rideout·Rafael D. Sorkin
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Abstract

One obtains Bell's inequalities if one posits a hypothetical joint probability distribution, or {\it measure}, whose marginals yield the probabilities produced by the spin measurements in question. The existence of a joint measure is in turn equivalent to a certain causality condition known as ``screening off''. We show that if one assumes, more generally, a joint {\it quantal measure}, or ``decoherence functional'', one obtains instead an analogous inequality weaker by a factor of $\sqrt{2}$. The proof of this ``Tsirel'son inequality'' is geometrical and rests on the possibility of associating a Hilbert space to any strongly positive quantal measure. These results lead both to a {\it question}: ``Does a joint measure follow from some quantal analog of `screening off'?'', and to the {\it observation} that non-contextual hidden variables are viable in histories-based quantum mechanics, even if they are excluded classically.

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David Craig, Fay Dowker, Joe Henson, Seth Major, David Rideout, Rafael D. Sorkin. 2006-12-11. A Bell Inequality Analog in Quantum Measure Theory. https://doi.org/10.1088/1751-8113%2F40%2F3%2F010

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